PROcalcitonin Impact on Antibiotic Reduction, adverSe Events and AVoidable healthcarE Costs (ProSAVE): A RCT

Inclusion Criteria: * Hospitalized adult patients ≥ 18 years of age * Suspected or confirmed pneumonia \<28 days at time of admission to the hospital (ED) who are prescribed antibiotics * Minimum of 2 (two) blood samples available for PCT value assessment within 24 hours of hospitalization Exclusion Criteria: * Patient has tested positive for SARS-CoV-2 * Non-hospitalized patients * Patients admitted to home health * Major surgeries, defined as any procedure in which an incision is made with the exception of superficial procedures (eyes, cornea, skin, dental procedures), organs removed, or normal anatomy altered (e.g. open thoracic, abdominal and/or major orthopedic surgery), in the past 1 month or expected surgical procedure or patient receiving antibiotics for surgical prophylaxis * Active metastatic cancer or neuroendocrine tumor or liquid tumor and/or on check point inhibitors within 3 months or has signs of mucositis (e.g. mouth lesions or intestinal bleeding) * Known pregnancy * Primary and acquired cell-mediated immune deficiency (HIV with CD4 \<350 cells/mm³; receipt of systemic chemotherapy and/or biologics in the past 3 months for reasons other than malignancy) * Infection where long course antibiotics are the standard of care(\>2 weeks) other than anti-inflammatory reasons. * Neutropenia (\<1,500 ANC) * Concomitant non-pulmonary bacterial infection that requires antibiotic therapy based on an active medical team decision * Antibiotics given for non-infectious indications (e.g. rifaximin for hepatic encephalopathy) * Patients with cystic fibrosis * Patients receiving dialysis * Patients with solid organ transplant, bone marrow transplant or stem cell transplant recipient * ST elevation myocardial infarction * Prior enrollment into this study within 30 days * Patient experiencing major trauma defined as any injury that could cause prolonged disability and/or an Injury Severity Score \>15, and/or burns or patient under extracorporeal circulation confirmed by a second research staff member. * Patient with acute viral hepatitis and/or decompensated severe liver cirrhosis (Child-Pugh Class C). * Patient with prolonged or severe cardiogenic shock, defined as decreased cardiac output leading to end organ injury (e.g. severe hypotension or AKI or oliguria or altered mental status or cool extremities or respiratory distress AND evidence of metabolic acidosis on lab testing) * Patient with pancreatitis, chemical pneumonitis or heat stroke * Active infection with invasive fungal pathogen (e.g. candidiasis, aspergillosis) or plasmodium falciparum malaria or mycobacteria * Patient under treatment with OKT3 antibodies, OK-432, interleukins, TNF-alpha and other drugs stimulating the release of pro-inflammatory cytokines or resulting in anaphylaxis. * Patient is under hospice care * Patient with ventilator associated pneumonia * Patients with untreated, active, and symptomatic autoimmune disease * Patients with empyema, abscess, or cavitary/necrotizing pneumonia * Patients actively enrolled in other clinical trial involving immunomodulatory therapy